1. Field of the Invention
The present invention relates to an apparatus for supplying a droplet on a substrate and a method of manufacturing a display apparatus using the apparatus for supplying the droplet on the substrate. More particularly, the present invention relates to an apparatus for supplying a droplet on a substrate capable of uniformizing an evaporation rate of the droplet having a volatile solvent, and a method of manufacturing a display apparatus using the apparatus for supplying the droplet on the substrate.
2. Description of the Related Art
A capacity of an information processing apparatus has been increased, and the information processing apparatus is widely used.
The information processing apparatus outputs data that is coded as an electric signal. The information processing apparatus includes a display apparatus so as to display an image corresponding to the electric signal.
The display apparatus may be classified into an emissive display apparatus and a non-emissive display apparatus.
The emissive display apparatus displays an image using a light emitting element. Examples of the emissive display apparatus are a cathode ray tube (CRT), a plasma display panel (PDP), a light emitting diode (LED), an organic light emitting display apparatus (OLED), etc.
The non-emissive display apparatus displays an image using a light reflection, a light diffusion, a light interference, etc. Examples of the non-emissive display apparatus are a liquid crystal display (LCD) apparatus, an electrochemical display (ECD) apparatus, an electrophoretic image display (EPID) apparatus, etc.
The OLED apparatus has various characteristics, for example, such as high luminance, light weight, thin thickness, low power consumption, etc.
When a high voltage is applied to a light emitting region, molecules in the light emitting region are excited, and the excited molecules are then dropped to a ground state to generate a light.
The OLED apparatus may also include an organic light emitting layer disposed between a pixel electrode and a counter electrode. The pixel electrode supplies the organic light emitting layer with electrons, and the counter electrode supplies the organic light emitting layer with holes so that the electrons are combined with the holes. Therefore, the molecules in the organic light emitting layer are excited. When the excited molecules are dropped to the ground state, a light is generated.
The organic light emitting layer of the OLED may be formed using a screen printing process, a nozzle printing process, etc.
In the screen printing process, a material that forms an organic light emitting layer is supplied to a substrate through openings of a mask.
In the nozzle printing process, a material that forms an organic light emitting layer, which has a volatile solvent, is dropped onto a substrate through a nozzle. In order to form the organic light emitting layer, a partition wall that surrounds the pixel electrode is formed. The material that forms the organic light emitting layer is dropped in a cavity formed by the partition wall. The dropped material that forms the organic light emitting layer is then dried to form the organic light emitting layer.
When the number of the pixel electrodes is increased, the material that forms the organic light emitting layer may not be dropped simultaneously. Therefore, the substrate may be divided into several groups and the material that forms the organic light emitting layer may be printed corresponding to each of the groups.
The evaporation rate of the material that forms the organic light emitting layer that is disposed on the peripheral portion of each of the groups may be different from the evaporation rate of the material that forms the organic light emitting layer that is disposed on the central portion of the group.
When the evaporation rates of the material disposed on the peripheral portion and the central portion, respectively, are different from each other, the thickness of the organic light emitting layer in the peripheral portion may be different from the thickness of the organic light emitting layer in the central portion so that the luminance corresponding to the peripheral portion may be different from the luminance corresponding to the central portion, thereby deteriorating the image display quality.